Heavy raw oils (such as residual oil) contain a large quantity of metal impurities such as Fe, Ca, Ni and V and intractable large molecule substances such as asphaltine and resin. These substances tend to cause metal depositing on the catalyst surface and the catalyst coking and deactivation in the production process, and therefore influence the product quality and reduce the operation period. Therefore, the hydrogenation conversion of asphaltine and the removal and accommodation of the metal impurities are the key issue in the hydrogenation process of heavy raw oils.
CN1690172A discloses a hydrogenation demetalling catalyst for residual oil, which catalyst contains a dual-pore alumina support and metal components such as molybdenum and/or tungsten and nickel and/or cobalt loaded on the support, wherein in the support, the pore volume of the pores having a pore diameter of 10-20 nm comprises 35-80% of the total pore volume, the pore volume of the pores having a pore diameter of 500-1200 nm comprises 15-60% of the total pore volume, and the pore volume of the pores having a pore diameter of <10 nm or from >20 nm to <500 nm, or >1200 nm comprises 540% of the total pore volume. It is said that this catalyst has a high hydrogenation demetalling activity and a low carbon deposit. Nevertheless, there is still a demand in the prior art to develop a catalyst with better properties.